Error into String

/tmp/test/check_cloudwatch_status-2.5.07.rb:382:in `+’: no implicit conversion of Fog::AWS::RDS::Error into String (TypeError)
from /tmp/test/check_cloudwatch_status-2.5.07.rb:382:in `rescue in ‘
from /tmp/test/check_cloudwatch_status-2.5.07.rb:336:in `’

I am getting above error. Please help me to resolve it.